You've been living outside of Germany, and your child has not been attending a recognized "German school abroad"?
In this case, your child would not immediately be required to go through the formal admission process to attend a state-approved school. The principal decides on the basis of legal prerequisites about the admission of your child and which grade to place your daughter or son to. In addition, the principal runs the admission process within a year, as the case may be.
One of our headteachers will be happy to advise you.